Magnetic Spin

[004594950]

When drawing out the electron configuration, can we make the spin downwards first or is it always spinning up first?

[MaxHuang Section 1B]

If I recall correctly from the lecture, you can make the electron spin downwards first, but when filling up the orbital you must have the electron spins facing the same direction before pairing the electrons. For example, if you have the element Carbon, you will have the electron configuration of [He] 2s^2 2p^2. When drawing the diagram of the Aufbau principle (building up principle) you can have the 2 electrons in the 2p orbital facing downwards (denoting their spin), but you cannot have one facing upwards and one facing downwards.

[Lucia Yang 3I]

Generally in problems and examples, they usually denote the first electron in each orbital (as you build up) with a positive spin. What Max says is definitely true and follows Hund's Rule where electrons in the same subshell (Carbon's 2p subshell from Max's example) will occupy different orbitals and with parallel spin. So, having the electron spin downwards first should be fine (but to follow convention, positive spins are usually first).